Bulk glassy alloys in (Fe, Co, Ni)-Si-B system

Multicomponent Fe75-x-yCOxNiySi8B17 glassy alloys were found to exhibit a distinct grass transition, followed by a supercooled liquid region before crystallization in a rather wide composition range of 7.5 to 45 at%Co and 7.5 to 60 at%Ni. The largest value of the supercooled liquid region defined by the difference between the glass transition temperature (Tg) and crystallization temperature (T-x), DeltaT(x) (= T-x- T-g) was 54 K for Fe30Co30Ni15Si8B17 Furthermore, the high reduced glass transition temperature (T-g/T-m) above 0.60 was obtained in the range of 15 to 30 at%Co and 37.5 to 52.5 at%Ni in the series of Fe75-x-yCoxNiySi8B17. The use of Fe30Co30Ni15Si8B17 with a large DeltaT, of 54 K and a high T-g/T-m of 0.65 enabled us to produce bulk glassy rods with diameters up to 1.2 mm. The T-g, T-x, saturated magnetization (4 pi I-s), and coercive force (H-cj) of the as-cast 1.2 mm rod alloy are 780 K, 834 K, 0.90 T, and 3.0 A/m, respectively In addition, the cast glassy rod exhibits Young's modulus of 110 GPa, compressive fracture strength of 2800 MPa and fracture elongation of 1.9%. It is noticed that the thermal stability, magnetic properties and mechanical properties are nearly the same as those for the melt-spun glassy ribbon. The first synthesis of Fe-Si-B base bulk grassy alloys with good soft magnetic properties and high mechanical strength is promising for the future development as a new type of engineering material.